1. What
Steering Gear Checks would you do before Setting Sail?
Prior
to a Ship's departure from any Port, the Steering Gear should be tested to
ensure satisfactory Operation. These
Tests should include:
Operation
of the Main Steering Gear
Operation
of the Auxiliary Steering Gear or the use of the Second Pump which acts as the
Auxiliary.
Operation
of the Remote Control Systems from the Main Bridge Steering Positions.
Operation
of Steering Gear using the Emergency Power Supply.
The
Rudder Angle Indicator Reading with respect to the actual Rudder Angle should
be checked.
The
Alarms fitted to the Remote Control System and Steering Gear Power Units should
be checked for Correct Operation.
Steering
Gear Header Tank Level should be checked.
2. What
checks should be carried out on a Breathing Apparatus Set before entering a
smoke filled compartment?
The
following checks should be carried out:
Ensure
the bottle is full,
Check
operation of low pressure whistle, and
Face
seal check should be carried out.
3. How
would you check that there was excess water in the Sump?
By
using Water Finding Paste.
4. What
is the purpose of the Over Current Protection Trip?
The purpose of the Over
Current Protection is to Trip the Generator in Overload situations. The Trip is usually set at 150% Operating
Capacity and has a time delay of usually 20 seconds. This allows for short periods of Overload
Currents. It also protects against a
Short Circuit in the Generator.
5. Fresh
Water supplied for Drinking and Culinary purposes must meet Specified Purity
Standards. How is this achieved?
These Standards are met by
passing the Fresh Water through a Hypochlorinator where the Water is Sterilised
by an excess dose of Chlorine provided as Hypochloride Tablets. It is then de-chlorinated in a Bed of
Activated Carbon to remove excess Chlorine.
Any Colour, Taste and Odour, which was present in the Water, will also
be removed by the Carbon.
Another
Method is to pass the Fresh Water through an Ultra Violet Steriliser.
6. How
do you purify HFO?
Heavy Fuel Oil is purified
using a Centrifugal Separator, which operates by the principle of Centrifugal
Force separating two liquids, in this case Fuel Oil and Water by means of a
Cylindrical Interface between the two.
The positioning of this Interface being very important for the correct
operation.
7. Why
is Simultaneous Injection of Fuel Oil and Starting Air into a Main Engine
Cylinder Undesirable and How is it Prevented
Simultaneous
Injection of Fuel and Starting Air into a Cylinder is Undesirable as it could
lead to an Explosion in the Start Air System.
It
is prevented by means of Interlock,
which prevents Fuel being Injected when the Air Start Auto Valve is
Open.
The
Interlock Operates a Stop Solenoid, which keeps the Fuel Rack at Zero Position.
8. What
are the requirements of a Fixed CO2 Fire Fighting Installation?
The
System must give 40% saturation of the Compartment to be filled.
85%
of the CO2 charge must be discharged into the Compartment within the first two
minutes.
9. State
the problem caused by electrical current being induced into shafting of
rotating machinery.
A problem that can arise
from currents generated in the rotor shaft due to stray magnetic fields, under
fault conditions these stray fields can be very large, these currents if
allowed to flow, would arc across the bearing surface and cause small craters
which would eventually destroy the bearings.
10.
What oxygen levels would you regard as safe to enter an enclosed space?
21%
11. What
type of Safety Valve is Fitted to a Boiler and at what Pressure does it Lift?
The
type of Safety Valves fitted to Boilers are High Lift Safety Valves and are
designed to Operate at 10% Boiler working pressure and must also be capable of
releasing all the Steam the Boiler can produce without the pressure rising more
than 10% over a set period: 15 min for
Tank Boilers and 7 mins for Water Tube.
The spring pressure, once set, is fixed and sealed by a Surveyor.
Note: The above Test is known as the Accumulation
of Pressure Test.
12. How
is a Medium Speed Engine Reversed (without CPP)?
In
Medium Speed Diesel Engines, reversing is achieved by the use of Duplicate Cams
for the Air Inlet Valves, Exhaust Valves and Fuel Pumps. Air Start Distributor Timing is also changed
by means of Camshaft Movement or by a Directional Air Supply being admitted to
the Start Air Distribution, to reposition Cams.
To
engage correct Cams for Ahead and Astern Movements, the Camshaft slides axially
in its Bearings. This movement is
controlled by the Camshaft Reversing Gear, which is normally a Servo
Piston. Motion of the Piston being
directly transmitted to the Camshaft.
Note: In a Slow Speed, only Duplicate Fuel Cams
required.
13. What
is the procedure for entering an enclosed space?
An
enclosed space entry permit is required which can only be obtained with the
permission of a responsible officer.
This permit will list the conditions to be met before entry.
The
space should be well ventilated before entry takes place; Before entry, oxygen levels must be checked
using an O2 Meter.
Another
person should remain at the entrance while the person is in the space, to
summon assistance if necessary and there should also be means of communications
arranged between the person within the space and the attendant.
Lifelines
and harnesses should be available at the entrance to the space.
If
the occupant appears to be in danger, the attendant should first raise the
alarm, but should not enter the space unless equipped with breathing apparatus
14.
What is Single Phasing of a Motor?
Single
Phasing is where one of the 3-phase's supplying the Motor becomes
disconnected. The Motor will continue to
run if this happens and can result in Motor Burnout. The effect of Single Phasing is to increase
the Current in the two remaining Lines and cause the Motor to become very noisy
due to uneven Torque produced.
15. Describe
an Inert Gas Generator
The
Inert Gas Generator burns fuel in designed quantities to produce perfect
combustion. This produces an exhaust
gas, which is largely nitrogen and carbon dioxide with a very small oxygen
content. The exhaust gases pass to a cooling and washing chamber to remove
sulphur and excess carbon. The washed or
scrubbed gas is now inert and passes to a distribution system for Fire
Fighting. The complete unit is arranged to be independently operated in order
to supply inert gas for as long as the fuel supply lasts.
On
tankers the inert gas can be supplied and used to blanket the oil cargo during
discharging operations. Empty tanks are
filled with gas and inert gas is blown out when oil is loaded.
16. What
is the Maximum Compressed Air Temperature that should leave an Air Compressor?
93°C
17. What
is the First Indication of a Leaking Exhaust Valve?
The
First Indication of a Leaking Exhaust Valve is a rise of Exhaust Gas
Temperature at the outlet of the Valve.
18. Where
would you expect to find a CO2 Extinguisher?
Machinery
spaces, particularly near electrical equipment, such as switchboards.
19. How
much foam is produced from a 9L Foam Extinguisher?
72
litres of Foam.
20. What
must the capability of Gravity Davits be with regards heel of ship?
The
Davits must be able to lower the Lifeboats when the Ship is heeled to 15
degrees on either side.
21. What
are the safety precautions to be observed prior to and during crankshaft
deflections?
Safety precautions to be observed when taking crankshaft
deflections are;
Ensure the starting system is shut down and isolated, with do not
start signs placed.
Ensure lubrication system is isolated, plus priming system.
Before using the turning gear, check with the bridge that it is
clear to so if engine is direct drive ( ie no clutch ).
Check indicator cocks are open to prevent undue load on the
turning gear.
Before turning the engine, ensure that there are no personnel in
the crankcase and there are no obstructions.
22. What
is done to ensure that a Lifeboat Engine will start when needed?
At least once every two weeks, but better still once a week the
Lifeboat Engine should be run, all Fuel and Oil Levels checked and the gearbox
should be operated i.e. Engine run astern and ahead to check Operation.
Most Engines are air cooled, but some are a combination of air and
water, in which case water level checked and if operating in cold climates
anti-freeze levels also.
Larger Lifeboat Engines will be battery started, therefore
condition of battery must be checked i.e.
S G of electrolyte and that electrolyte is covering cell plates.
23 How can Exhaust Valve Leakage
be confirmed?
Exhaust Valve Leakage can be confirmed by taking an Indicator
Card, the Card should be taken with Fuel "On" and "Off" the
Unit. If the Valve is leaking, the
compression pressure and maximum pressure will be low
24 How is a liner gauged?
A cylinder liner is gauged using a ball ended micrometer , the
micrometer should be checked for accuracy by first checking it using a set
datum, normally supplied with the engine when built for this purpose. A
manufacturers measuring gauge with set positions on it vertically is used in
conjunction with the inside micrometer. ( see sketch )
Before readings are taken, the temperature inside the liner is
taken.
The readings are then taken in the port to stbd directions and in
fore an d aft directions.
To get an accurate reading, the manufacturers gauge is placed in
the liner in one of the above positions, then a chalk mark is made in the holes
where the micrometer is placed, the gauge is then placed on the opposite side,
and the readings are taken using the chalk mark as a reference point.
The " rocking" method is then used to get an accurate
reading with the micrometer, ie the micrometer is moved up and down, side to
side, until the micrometer is just touching the opposite side from the gauge,
the chalk mark aiding this procedure.
25 What
is the Function of an Evaporator in a Refrigeration System?
The Function of the Evaporator is to boil off the liquid
Refrigerant, at the same time cooling the air.
The design of the System and Evaporator should be such that all Liquid
Refrigerant is boiled off and the gas slightly superheated before returning to
the Compressor.
26 What
Fittings would you expect to find on a Start Air Receiver?
Fittings found on a Receiver are:
Safety Valve, Fusible Plug, Isolating Valve to Main Air Start System,
Filling Valve from Compressor, Drain Valve, Valve to Control Air, Valve to
Whistle, Pressure Gauge.
27 What
is "Water Hammer" and its danger?
When steam lines are shut down it is possible from various causes
for them to fill with water. If steam is
allowed to enter a line with water, the steam starts to move the water down the
line. The steam in contact with the
water eventually condenses and a vacuum is formed causing the water to be
pulled back to the valve which has just been opened and striking it with a
heavy blow, often fracturing the valve.
If the valve fractures, it may end disastrously with risk of loss of
life.
28. What
advantage do Inert Gas producing units used for Fire Fighting Installations
have over CO2 and Halon Systems?
Inert Gas Producing Units have the advantage of being able to
continuously produce Inert Gas. A bottle
storage system, such as CO2 or Halon Flooding is a "one shot" Fire
Extinguisher which leaves a ship unprotected until further gas supplies can be
found.
29 Is
the Code of Safe Working Practises Law?
Yes it is Law.
30 How
is a Liferaft Launched?
A Liferaft is simply launched by releasing it from its lashings, a
painter is secured to the Ship and the Liferaft container is thrown over the
side. Inflation takes place
automatically, the container bursting open and the Liferaft floats clear. A pressurised cylinder of CO2 is used to
inflate the raft. Liferafts must
normally be boarded from water level, dry if possible.
31 Where
On Board a Ship would you find Information on the Carriage of Hazardous
Substances?
Information on the Carriage of Hazardous Substances would be found
in the IMDG (International Maritime Dangerous Goods Code), which would normally
be found on the Bridge.
32 Why
are High and Low Suctions fitted on Fuel Oil Service Tanks?
The High and Low Suctions are a Safety Feature to prevent
invertent Shut Down of Main Engines, Generators and Boilers due to Water
Contamination of the Fuel. Normally the
Low Suction is kept in use. If any Water
should find its way into the Fuel and Service Tank, it will gradually separate
towards the Tank Bottom. When it becomes
apparent Water is present by finding it at the Tank Drains or by Operation of
the Engine, it is possible to bring the High Suction into Operation and avoid
Shut Down.
33 How
does a Foam Nozzle work?
The foam nozzle works on the Venturi Principle where air is drawn
into the nozzle aerating the foam solution for good quality fire fighting foam.
34 Give
a Shipboard use of Spheroidal Cast Iron and the Properties that make it
suitable for this use.
Cylinder Heads and Liners.
It has high compressive strength qualities and also good wear
resistive qualities.
35 Why
do you require Earth Lamps on 220V Distribution Board when you have them on the
Main Switchboard?
You require Earth Lamps on the 220V Distribution Board as well as
the Main Board, due to the air gap in step down transformer, i.e. 440V Earth
Lamps can not detect Earth on 220V systems due to the gap.
36 What
should be used with Breathing Apparatus Sets when entering a Space or
Compartment?
A time in/time out board should be used. This board will normally have a built in
clock. On this board the time the wearer
enters a space is noted, plus bottle number and pressure, the time the wearer
is due out is calculated as the time the low-pressure whistle operates at. This gives the wearer time to exit.
37Where
would you expect to find a Foam Extinguisher?
It would be located in the Engine Room, in the vicinity of
Flammable Liquids, also Bunker Stations.
38 What
is regarded as an enclosed space?
An enclosed space is a space that cannot be assumed to contain
oxygen.
These are spaces such as a duct keel, a double bottom tank, a
cofferdam, boiler, etc.
39 Would
you enter an enclosed space if the oxygen levels were recorded as 19% or below?
No
40 Explain
Heavy Oil Fuel System from Bunker Tanks to Engine.
Fuel is pumped from the Fuel Oil Double Bottoms via a Transfer
Pump to a Fuel Oil Settling Tank where it is heated. The Fuel Oil Purifiers/Centrifuges take
suction from the Settling Tank via Purifier Heaters, pass through the
Purifiers, where any water and impurities are removed and passed on to the
Service Tank which also has a set of Heating Coils.
From the Service Tank the Fuel then passes via a Flowmeter to the
Mixing Tank, from where the Booster Pumps take suction, discharging to the Fuel
Oil Heaters, where the correct Fuel Oil Temperature/Viscosity is achieved for
correct Fuel Combustion in the Engine.
The Fuel then passes through the Viscosity Regulator which controls the
Heater Temperature, then on to the Fuel Oil Filters (which are heated), to the
Fuel Pumps, then to the Fuel Injectors via Double Skin/Wall High Pressure Pipe.
Any surplus Fuel returns via a Regulating Valve from the Fuel
Pumps back to the Mixing Tank.
Diesel Oil can also be used in the System and is fed to the System
via a three-way valve.
Note: When Diesel is used,
no heating is required.
41 What
are you looking for when you Pull a Piston?
When you Pull a Piston, you are looking for any damage to the
Piston Crown, including cracks.
The Condition of Piston Rings are checked, plus Piston Ring
Grooves.
Check for any scuffing of Piston Skirt
Check condition of Top End Bearing Bush and Gudgeon Pin, plus
clearance between Pin and Bush.
Check Lubrication Bores are clear on under side of Piston.
42 What
is meant by the Term, Type Ex'd'?
Ex'd' = Flame Proof Enclosure.
This is an enclosure that will withstand an Internal Explosion of
Flammable Gas within itself and dissipate heat from that explosion before
reaching outside atmosphere, which could ignite the gas in surrounding
atmosphere, i.e. a Ship's Battery Locker could be classed as Ex'd'.
43 What
are the two main functions of a cable gland?
The two main functions of a cable gland are, to prevent ingress of
water and to hold the cable securely in position.
44 What
is the difference between Cylinder Lub Oil of Trunk Piston Engines and
Crosshead Engines?
The Cylinder Lub Oil used in Trunk Piston Engines is the same as
the Main Engine Oil, usually in Trunk Piston Engines, the quality of Fuel used
is better than that of Crosshead.
Therefore the TBN (Alkali content of the Oil) is lower.
Cylinder Lub Oil used in Crossheads have a high TBN, as the Fuels
used are of cheaper quality and a high amount of acidic properties are formed
from combustion, hence needing a higher TBN content to neutralise these acids
to prevent corrosion.
45 What
different types of Fire Fighting Foam are there?
AFFF - synthetic type
Protein based Foams (Ox's blood)
Which can be low expansion for use on decks etc for fire-fighting,
or
High expansion, which can be used in Machinery Spaces.
46 How
are HFO Impurities Removed?
Impurities in Heavy Fuel Oils are removed by centrifugal
separators i.e. purifiers and clarifiers.
Liquids and Sludges being removed by Purifiers, Solids by Clarifiers.
47 What
are the Marpol Restricted Areas?
The Marpol Restricted Areas are:
The Mediterranean Sea, Baltic Sea, Black Sea, Red Sea, "Gulf
Areas", North Sea, Antarctic, wider Caribbean Region including Gulf of
Mexico and the Caribbean Sea.
48 What
is an indication in the Exhaust Gas of Good Combustion?
Grey Smoke indicates Good Combustion.
49 Give
an example of Densities of Oils and Gravity Disc Sizes Used.
Heavy Fuel Oil: 950kg/m3
Lub Oil: 870kg/m3
Diesel Oil: 880kg/m3
50 What
is the Primary Function of the Expansion Valve in a Refrigeration System?
The Primary Function of an Expansion Valve in a Refrigeration
System is to regulate the Flow of Refrigerant from the H P side to the L P side
of the System. The pressure drop causing
the Saturation Temperature to drop, enabling it to boil off at the Low
Temperature of the Evaporator.
51 What
is fitted in a Foam or Water Type Fire Extinguisher that ensures liquid, not
gas comes out on discharge.
A diptube or internal pipe is fitted in the Fire Extinguisher,
which is connected to the extinguisher hose and travels to the bottom of the
extinguisher.
52How
do you take sterntube bearing weardown ?
This is taken in drydock, on the outboard side of the sterntube is
a plug that can be removed to allow for access to check the weardown by means
of depth gauge, the reading taken will be compared to readings from new.
53 What
is meant by the Term, Type Ex'i'?
Ex'i' = Intrinsically Safe.
Equipment with circuits that do not generate enough heat to ignite
a gas. This generally means limiting
circuits to less than 30V, 50mA.
54 What
are the two Main Types of Battery commonly used on board Ships?
Lead Acid and Alkaline.
55 What does a Positive Displacement Pump require
that a Centrifugal Pump does not?
A Relief valve.
56 What
are the rough Lub Oil Pressures on the following, on a 2 stroke Engine: Piston Cooling; Crosshead Bearings and Main Bearings?
Piston Cooling: 6-7 bar
Crosshead Bearing: 4-5 bar
Main Bearing: 2.5-3 bar.
57
What is the Normal Reading on and Insulation Test Meter?
Infinity 00 is a normal
reading, but readings should be kept above 5MW.
58
Why are Quick Closing Valves fitted in a Fuel System and how can they fail to
operate?
Quick Closing Valves are fitted in Fuel Systems so that in the
event of a Fire in the vicinity of these Systems or a Fracture or Break in
these Lines, the System can be shut down rapidly and remotely.
They may fail to operate if not maintained or tested regularly.
59
How can the bottom end bearing clearance be checked?
The bottom end clearance can be checked by using a set of feelers
to get the clearance between the bottom end shells and the crank pin.
Another method is to measure the inside diameter of the bearing
shells and the outside diameter of the crank pin and difference between the
two, will be your clearance.
60
What Safety Devices are Fitted to a Start Air Line?
Non Return Valve, Flame Traps/Arrestors, Bursting Discs and Safety
Valves.
61
What would cause Excessive Exhaust Temperatures?
On a Single Cylinder, it could be an Incorrect Fuel Pump Timing
i.e. late Injection causing after-burn,
too much Fuel, leaking Fuel Injector or burnt out Exhaust Valve. If all Exhaust Temperatures were High, it
could be due to High Scavenge Temperature, Charge Air Cooler Fouled, Turbo
Charger Air Filters Dirty or Fouled, High Engine Load.
62
Describe a Self-Contained Breathing Apparatus Set.
The Self-contained Breathing Apparatus Set usually consists of one
or two cylinders of compressed air kept in a harness, which is carried on the
back. Cylinders usually being charged to
a pressure of around 200-240 bar. The
high pressure air is fed through a reducing valve and then to a demand valve,
which can be set in positive pressure mode, that will supply a constant demand
of air, or in demand mode, which will only supply air as the wearer
demands. A non-return valve permits
breathing out to atmosphere.
The set incorporates a warning whistle that sounds on low air
pressure.
A standard cylinder will allow for about 20-25 minutes operation,
but this will also depend on a few factors, such as workload of wearer.
63
What is the Principle Operation of a Heat Detector?
This type of Heat Detector uses two bi-metalic strips/coils attached to a vertical support
bracket. When temperature is present,
the bi-metalic strips will start to move, at a fixed temperature the first
strip will hit a stop, the second strip continuing to move, thus the contact is
made and triggers the alarm.
64
What is the purpose of the two sets of relief valves on a Bulk CO2 System.
The purpose of the two sets of relief valves on a Bulk CO2 System
is that one set being an L P Set being set at 24.5 bar and designed to relieve
excess pressure to atmosphere in the event of over pressure.
The H P Set is at 27 bar and is required to discharge into the
Compartment, i.e. in the event of a Fire in the Bulk CO2 Compartment, this
causes a rapid rise in pressure and in theory CO2 will discharge into the
compartment, extinguishing the fire.
65
What would you do in the Case of a Crankcase Explosion?
When the Alarm sounds, the Engine Speed must be reduced to slow
and permission obtained to stop the Engine.
Inform Chief Engineer.
When an Engine has stopped under Alarm Conditions under no
circumstances must any doors or inspection windows be opened.
Oil should continue to be circulated and time allowed for the Hot
Spot to cool.
The early opening of doors could cause an explosion due to ingress
of air.
During Cooling down Period, the Engine Room Staff must keep clear
of the side of the Engine fitted with Explosion Doors.
After a period of at least 20 minutes, stop the Lubricating Oil
Pump, cut off all Air and engage Turning Gear.
The Access Doors should then be opened and Personnel must keep
clear of possible flames. Under no
circumstances should naked lights be used nor should anyone be permitted to
smoke.
Examination should then take place for any squeezed out bearing
metal or loose bearing metal in the Crankcase.
Heat discoloured Metal Parts or blistering of Paintwork must be
investigated. The Ceiling of the
Crankcase and Guide Bars should also be observed. If the Crankcase is clear, the Camshaft Drive
and Main Thrust Bearing should be inspected for signs of overheating.
Should any damage be found, then a permanent repair must be put in
hand immediately.
After repair, Lub Oil should be checked for Free Flow.
The Engine should then be run in i.e. 15 mins, then check
components for signs of overheating, then half an hour at half speed, again
check, then one hour full speed, then check again.
Note: Varying times have
been quoted for the Cooling Down Period and no set rules are available, but,
the longer the time taken, the greater the Safety Factor.
66
Why and what type of Valves are Boiler Feed Check Valves?
The Feed Checks are Non-Return type Valves and are fitted in
pairs, one being the Main, the other, the Standby or Auxiliary and they must
give an indication of Open or Closed Positions.
They are of Non-Return type to prevent Back Flow of Boiler Pressure down
the Feed Line.
67
What is Sequential Starting?
Sequential Starting is the automatic starting of essential
equipment when power is returned after a total power failure, i.e. equipment such as Steering Gear.
68
How does a Turbo-charger work?
The Turbo-charger mainly consists of a Turbine and a Compressor
assembled as a single unit on a Shaft.
The exhaust gas from the Engine flows through a water-cooled gas
inlet (cooling from Engine Jacket Water System) to a nozzle ring, which directs
gases at the Turbine Rotor Blading. This
force causes the Rotor to rotate at High Velocity. The gases leaving via a water-cooled gas
outlet casing, to an exhaust pipe and to atmosphere.
The air required for the Diesel Engine is drawn in by the
Compressor via a combined Silencer/Filter.
The entry passage after the filter is then divided into splitters which
prevent draught losses and guide the air to the compressor, the air being drawn
in axially by the compressor and discharged radially at high velocity to the
diffuser, which changes much of the velocity to pressure. From the diffuser the air passes into the
Volute Casing, changing the rest of the airs Kinetic Energy to pressure before
being discharged to the Charge Air Cooler and to the Engine for Combustion.
69
What happens to the CO2 System in Drydock?
What
happens to the CO2 System in Drydock?
70
Describe how Synchronising Lamps are used to Parallel a Generator.
This is normally used as a back-up or alternative way to the
Synchroscope, the Lamps are connected between the Incoming Generator and the
Bus-bars. The "Sequence
Method" is the preferred one as it displays a rotation of Lamp Brightness,
which indicates, whether the incoming machine is running fast (clockwise) or
slow (anti clockwise). As with the
Synchroscope, the Lamp Sequence must appear to rotate slowly clockwise. Correct synchronisation occurs when the top
or "Key" lamp is dark and the two bottom lamps are equally bright.
71
State the regulations regarding the Emergency Fire Pump.
The Emergency Fire Pump is to be located remote from the Machinery
Space and with Independent Means of Power, which could be a diesel engine or
from the Emergency Switchboard.
72
What would cause the Level of the Lub Oil Sump or Drain Tank to Rise?
Water entering the oil, or fuel or even a Lub Oil Filling Valve
passing.
73
How many pumps are there in the Engine Room that you can pump Bilges with?
A Bilge Pump which is normally Positive Displacement.
The others may vary from Ship to Ship, but can be the Ballast
Pump, General Service Pump and Main Sea Water Cooling Pump. These Pumps are only used for Pumping Bilges
in the event of an emergency and have an Emergency Bilge Suction/Injection
Valve connected to them.
74
How can currents of this type be avoided or reduced?
Currents of this sort may be avoided in machines by insulating one
or both bearings, the insulation may be at the bearing housing or more commonly
, beneath the pedastal where it seats on the bedplate stool, the insulation of
one bearing is more usual, but insulating both allows insulation to be checked,
where both are insulated, an earth strap is fitted. Also holding down bolts are
insulated.
75
What is Uniflow Scavenging?
With Uniflow Scavenging, the Incoming Air enters at the Lower End
of the Cylinder and Leaves at the Top.
The Outlet at the Top of the Cylinder being a Large Exhaust Valve. The advantage of Uniflow is the simple design
of the Liner, plus it is the most efficient.
76
On what type of Fires would you use a Foam Extinguisher?
Class B Fires: Fires
burning liquids such as lubricating oil and fuels.
77
What is the Function of a Fuse?
The function of a Fuse is to give Short-circuit Protection and
also Overload Protection and operates in milliseconds
78
What Interlocks are there on the Start Air System?
An
Interlock to prevent Fuel being Injected
An
Interlock on Turning Gear and
An
Interlock CPP System, pitch has to be on Zero before Starting Engine.
78
What type of Pumps are used for Pumping Bilges in an Emergency?
These
Pumps are normally High Capacity Centrifugal Pumps.
79
What are the Causes of Single Phasing?
Single
Phasing can be caused when one of the three back up fuses blows or if one of
the contactor contacts is in open circuit.
80
Where on the ship is the Emergency Generator Located?
The
Emergency Generator is located remotely from the Engine Room, usually on the
Accommodation Deck or at Weather Deck Level or above.
81
What action would you take if you spotted oil in the Gauge Glass of a Boiler?
The
action to be taken would be to scum the boiler and blow down the gauge
glass. Then the source of contamination
investigated and stopped.
If
the oil contamination is excessive, then alternative heating source must be
found for engine fuel, if running on heavy or change over onto diesel.
The
boiler should then be shut down, allowed to cool and vent.
The
top door of the drum should then be removed and the oil overflowed from the
drum.
Ideally
the boiler should be degreased before re-using.
Source
of contamination must be found and remedied.
82
What are the Symptoms of a Scavenge Fire?
When
a Scavenge Fire has broken out, the Scavenge Air Temperature and the Exhaust
Temperature of the Unit in question will increase considerably and in some
cases the Turbocharger may start Surging.
Even Hot Spots on the Scavenge Trunking can be found.
83
What would you do in the event of a Scavenge Fire?
If
a Scavenge Fire were to start, the two main objectives are to confine the
Scavenge Fire to the Scavenge Space and to minimise damage to the Engine.
In
the event of the Fire breaking out, inform Bridge that the Engine is to be
brought to Dead Slow Ahead and also inform the Chief Engineer.
The
Fuel should be cut off to that particular Cylinder. The Cylinder Lub Oil should be increased to
prevent seizure and wear.
If
Fixed Fire Fighting Equipment is attached to the Scavenge Trunking, this can be
brought into operation, depending on severity of situation. But in most cases the Fire will generally
subside within 5-15 minutes.
Once
the Fire is out and Navigational Circumstances allow it, the Engine must be
Stopped.
Do
not open Scavenge Space Doors or Crankcase Doors before Site of Fire has cooled
down. When opening up, care must be
taken to keep clear of any flame.
After
opening up, all scavenge spaces must be thoroughly cleaned and all debris
removed. The Piston Rods and Cylinder
Liner should be examined for surface blemishes, straightness, etc., and the
Diaphragm Glands (Stuffing Box) examined to ensure that they are operational
and not damaged.
Also
Piston Rings should be checked, as Blow By may have been the Ignition Source of
the Fire. If possible the Piston Head in
question should be renewed at the earliest possible moment and the damaged Unit
overhauled.
On
Engines fitted with Tie Bolts, it may be necessary to re-tighten the Bolts
adjacent to the Fire.
When
starting the Engine again, care must be taken after switching on the Fuel to
the Cylinder in question, and that also the Cylinder Lub Oil quantities are
reduced to normal.
84
What would happen if the Lub Oil Pressure just dropped to Zero?
The
Engine would Shut Down on the Low Lub Oil Pressure Trip.
85
Draw and explain how Earth Lamps works.
A
direct earth on one pole will short circuit it's lamp, causing the other two to
shine brightly.
85
What is the Purpose of the Scum Valve on a Boiler?
The
Scum Valve on a Boiler is connected to a shallow dish positioned at the normal
water level of the Boiler and enables the Blowing Down or Removal of Scum and
Impurities from the Water Surface.
86
What are the most common faults that mechanicl / hydraulic governors are prone
to?
The
most common fault and relates to 50% of them is due to oil condition or the
wrong type of oil being used.
Other
faults are worn or broken springs, or worn governor drives.
The
engine hunting due to air in the governor hydraulic oil system.
87
What is a good practice before using a Dry Powder Extinguisher?
It
is good practice to give a Dry Powder Extinguisher a shake before use, as the
Extinguisher could have been lying for a while causing the powder to clog up.
88
How would you Blow Down a Boiler Gauge Glass?
Close
the Water and Steam Cocks on the Gauge Glass and open the Drain.
Then
open the Steam Cock - a strong jet of Steam should be seen from the Drain.
Close
the Steam Cock.
Open
the Water Cock - a strong jet of Water should be observed from the Drain.
Close
the Water Cock and then close the Drain.
Then
open the Water Cock, the water will rise in the Gauge, above normal level.
Then
open the Steam Cock, the Water should then settle down, finding its correct
level.
89
How are accurate reading ensured while taking crankshaft deflections?
Accurate
readings are ensured by checking the condition of load of the ship, i.e
crankshaft deflections are best taken when the ship is unloaded.
The
crankcase temperature is taken into consideration.
Competent
personnel take the readings
Where
the readings are taken near the turning gear end of the crankshaft, on larger
engine, consideration may have to be taken for these readings as there may be
slight lift in the crankshaft from the turning gear.
90
What are Batteries used for On-Board Ships?
They
are used for supplying essential power to:
Radio Equipment, Telephone Exchange, Fire Detection, General Alarm
Circuits, etc. These Systems are often
supplied from two sets of batteries worked on a regular charge/discharge cycle.
They
are also used as Emergency Supplies, i.e. for Emergency Generator Start-up and
Emergency Lighting. Being used in this
case in a "stand-by" role to give power when Main Supplies fail.
91
Fires are classified according to the types of material, which are acting as
the source, what are these Classifications?
Class
A -
Fires burning wood, glass fibre, upholstery and furnishings
Class
B -
Fires burning liquids such as lubricating oil and fuels
Class
C -
Fires burning gas fuels such as liquefied petroleum
Class
D -
Fires burning combustible metals such as magnesium and aluminium
Class
E -
Fires burning any of the above materials together with high voltage
electricity.
92
What percentage of Engine Speed does the Overspeed Operate at?
10-15%
maximum Speed.
93Explain
and sketch a Funnel Inert Gas System.
In
a Boiler Funnel Inert Gas System, exhaust gas is taken from the Boiler Uptakes
and passed through a scrubber tower where the gas is cleaned with sulphur and
excess carbon being removed.
The
Gas which by then is considered inert and mainly contains Nitrogen and Carbon
Dioxide with less than 5% Oxygen, is then supplied via blowers and deck seal
which acts as a non-return valve, along deck pipes to cargo banks.
The
inert gas being used to blanket the oil cargo during discharging
operations. Empty tanks are filled with
gas and the inert gas is blown out when oil is loaded.
94
Why is a Jacket Water Safety Valve fitted on Air Compressors?
It
is fitted to relieve excess pressure in the Cooling System should a Cooler Tube
burst and Compressed Air escape.
95
What Conditions are Necessary to Parallel two Generators?
The Speed of both Machines must be the Same i.e. the Frequency and
the Voltages must be the Same and in Phase.
96
The Main Engine Cylinder Lubricating Oil Tank is empty, oil drums are on the
Main Deck beside run down Pipes to the Tank and air is handy - What do you do?
If need be, the engine should be stopped to allow filling of the
tank. Under no circumstances should you
use the air hose to pressurise the drums to speed up the process. Oil drums are not a pressure vessel and it
could lead to a fatality.
97
Where would you expect to find a Dry Powder Extinguisher?
It is usually located near Electrical Equipment in the Machinery
Space and elsewhere on the Ship.
98
What action would you take in the event of Fire breaking out in the Machinery
Space?
If a Fire breaks out, the alarm should be raised and the Bridge
informed immediately. If the Ship is in
Port, the Local Fire Authority should be called. If possible, an attempt should be made to
extinguish or limit the fire by any means possible (a Fire in its first few
minutes can usually be readily extinguished).
Ventilation fans should be stopped (should stop automatically on
activation of fire alarm). Openings to
the space should be sealed to reduce the supply of air to the fire and to
prevent it spreading. Any fuel lines
feeding the fire or threatened by it should be isolated. If practicable, combustible materials adjacent
to the Fire should be removed.
After the Fire has been extinguished, precautions should be taken
against spontaneous re-ignition.
Personnel, unless wearing breathing apparatus, should not re-enter
a space in which a fire has occurred before it has been fully ventilated.
99
With regards Dry Powder Extinguishers, what testing and maintenance should be
carried out?
Being a pressure vessel, the container is tested to 35 bar every
four years.
Operating mechanism checked, where practical every three months.
100 What is the range of a Foam Fire
Extinguisher?
The range of a Foam Fire Extinguisher is roughly 7m.
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